To retrieve data exposed by the API, API Platform uses classes called data providers. A data provider using Doctrine ORM to retrieve data from a database is included with the library and is enabled by default. This data provider natively supports paged collections and filters. It can be used as is and fits perfectly with common usages.
However, you sometime want to retrieve data from other sources such as another persistence layer, a webservice, ElasticSearch or MongoDB. Custom data providers can be used to do so. A project can include as many data providers as it needs. The first able to retrieve data for a given resource will be used.
For a given resource, you can implement two kind of interfaces:
CollectionDataProviderInterface
is used when fetching a collection.ItemDataProviderInterface
is used when fetching items.Both implementations can also implement a third, optional interface called ‘RestrictedDataProviderInterface’ if you want to limit their effects to a single resource or operation.
In the following examples we will create custom data providers for an entity class called App\Entity\BlogPost
.
Note, that if your entity is not Doctrine-related, you need to flag the identifier property by using @ApiProperty(identifier=true)
for things to work properly (see also Entity Identifier Case).
First, your BlogPostCollectionDataProvider
has to implement the CollectionDataProviderInterface
:
The getCollection
method must return an array
, a Traversable
or a ApiPlatform\Core\DataProvider\PaginatorInterface
instance.
If no data is available, you should return an empty array.
<?php
// api/src/DataProvider/BlogPostCollectionDataProvider.php
namespace App\DataProvider;
use ApiPlatform\Core\DataProvider\CollectionDataProviderInterface;
use ApiPlatform\Core\DataProvider\RestrictedDataProviderInterface;
use ApiPlatform\Core\Exception\ResourceClassNotSupportedException;
use App\Entity\BlogPost;
final class BlogPostCollectionDataProvider implements CollectionDataProviderInterface, RestrictedDataProviderInterface
{
public function supports(string $resourceClass, string $operationName = null, array $context = []): bool
{
return BlogPost::class === $resourceClass;
}
public function getCollection(string $resourceClass, string $operationName = null): \Generator
{
// Retrieve the blog post collection from somewhere
yield new BlogPost(1);
yield new BlogPost(2);
}
}
If you use the default configuration, the corresponding service will be automatically registered thanks to autowiring. To declare the service explicitly, or to set a custom priority, you can use the following snippet:
# api/config/services.yaml
services:
# ...
'App\DataProvider\BlogPostCollectionDataProvider':
tags: [ { name: 'api_platform.collection_data_provider', priority: 2 } ]
# Autoconfiguration must be disabled to set a custom priority
autoconfigure: false
Tagging the service with the tag api_platform.collection_data_provider
will enable API Platform Core to automatically
register and use this data provider. The optional attribute priority
allows to define the order in which the
data providers are called. The first data provider not throwing a ApiPlatform\Core\Exception\ResourceClassNotSupportedException
will be used.
The process is similar for item data providers. Create a BlogPostItemDataProvider
implementing the ItemDataProviderInterface
interface:
The getItem
method can return null
if no result has been found.
<?php
// api/src/DataProvider/BlogPostItemDataProvider.php
namespace App\DataProvider;
use ApiPlatform\Core\DataProvider\ItemDataProviderInterface;
use ApiPlatform\Core\DataProvider\RestrictedDataProviderInterface;
use ApiPlatform\Core\Exception\ResourceClassNotSupportedException;
use App\Entity\BlogPost;
final class BlogPostItemDataProvider implements ItemDataProviderInterface, RestrictedDataProviderInterface
{
public function supports(string $resourceClass, string $operationName = null, array $context = []): bool
{
return BlogPost::class === $resourceClass;
}
public function getItem(string $resourceClass, $id, string $operationName = null, array $context = []): ?BlogPost
{
// Retrieve the blog post item from somewhere then return it or null if not found
return new BlogPost($id);
}
}
If service autowiring and autoconfiguration are enabled (it’s the case by default), you are done!
Otherwise, if you use a custom dependency injection configuration, you need to register the corresponding service and add the
api_platform.item_data_provider
tag to it. As for collection data providers, the priority
attribute can be used to order
providers.
# api/config/services.yaml
services:
# ...
'App\DataProvider\BlogPostItemDataProvider': ~
# Uncomment only if autoconfiguration is disabled
#tags: [ 'api_platform.item_data_provider' ]
ItemDataProvider
In some cases, you may need to inject the Serializer
in your DataProvider
. There are no issues with the
CollectionDataProvider
, but when injecting it in the ItemDataProvider
it will throw a CircularReferenceException
.
For this reason, we implemented the SerializerAwareDataProviderInterface
:
<?php
// api/src/DataProvider/BlogPostItemDataProvider.php
namespace App\DataProvider;
use ApiPlatform\Core\DataProvider\ItemDataProviderInterface;
use ApiPlatform\Core\DataProvider\SerializerAwareDataProviderInterface;
use ApiPlatform\Core\DataProvider\SerializerAwareDataProviderTrait;
use ApiPlatform\Core\Exception\ResourceClassNotSupportedException;
use App\Entity\BlogPost;
final class BlogPostItemDataProvider implements ItemDataProviderInterface, SerializerAwareDataProviderInterface
{
use SerializerAwareDataProviderTrait;
public function supports(string $resourceClass, string $operationName = null, array $context = []): bool
{
return BlogPost::class === $resourceClass;
}
public function getItem(string $resourceClass, $id, string $operationName = null, array $context = []): ?BlogPost
{
// Retrieve data from anywhere you want, in a custom format
$data = '...';
// Deserialize data using the Serializer
return $this->getSerializer()->deserialize($data, BlogPost::class, 'custom');
}
}
ApiPlatform provides a few extensions that you can reuse in your custom DataProvider. Note that there are a few kind of extensions which are detailed in their own chapter of the documentation. Because extensions are tagged services, you can use the injection of tagged services:
services:
'App\DataProvider\BlogPostItemDataProvider':
arguments:
$itemExtensions: !tagged api_platform.doctrine.orm.query_extension.item
Or in XML:
<services>
<service id="App\DataProvider\BlogPostItemDataProvider">
<argument key="$itemExtensions" type="tagged" tag="api_platform.doctrine.orm.query_extension.item" />
</service>
</services>
Your data provider will now have access to the core extensions, here is an example on how to use them:
<?php
// api/src/DataProvider/BlogPostItemDataProvider.php
namespace App\DataProvider;
use ApiPlatform\Core\Bridge\Doctrine\Orm\Util\QueryNameGenerator;
use ApiPlatform\Core\DataProvider\ItemDataProviderInterface;
use ApiPlatform\Core\DataProvider\RestrictedDataProviderInterface;
use ApiPlatform\Core\Exception\ResourceClassNotSupportedException;
use App\Entity\BlogPost;
use Doctrine\Common\Persistence\ManagerRegistry;
final class BlogPostItemDataProvider implements ItemDataProviderInterface, RestrictedDataProviderInterface
{
private $itemExtensions;
private $managerRegistry;
public function __construct(ManagerRegistry $managerRegistry, iterable $itemExtensions)
{
$this->managerRegistry = $managerRegistry;
$this->itemExtensions = $itemExtensions;
}
public function supports(string $resourceClass, string $operationName = null, array $context = []): bool
{
return BlogPost::class === $resourceClass;
}
public function getItem(string $resourceClass, $id, string $operationName = null, array $context = []): ?BlogPost
{
$manager = $this->managerRegistry->getManagerForClass($resourceClass);
$repository = $manager->getRepository($resourceClass);
$queryBuilder = $repository->createQueryBuilder('o');
$queryNameGenerator = new QueryNameGenerator();
$identifiers = ['id' => $id];
foreach ($this->itemExtensions as $extension) {
$extension->applyToItem($queryBuilder, $queryNameGenerator, $resourceClass, $identifiers, $operationName, $context);
if ($extension instanceof QueryResultItemExtensionInterface && $extension->supportsResult($resourceClass, $operationName, $context)) {
return $extension->getResult($queryBuilder, $resourceClass, $operationName, $context);
}
}
return $queryBuilder->getQuery()->getOneOrNullResult();
}
}
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